I see this in my french city, there's a particular spot on my commute where my phone (mediatek) will report 2 bars of 5G but speeds will actually be around 3G. I've also noticed other people on the tram having their videos buffer at that spot, so it's not just me. The carriers do not care, of course.

I think there's just some of these areas where operational conditions make the towers break in some specific way.